1. Technical Field
This invention relates generally to portable radiotelephones that have a protective cover pivotally mounted to the body of the phone, and more particularly, to such a radiotelephone having a microphone disposed in the body in communication with an acoustical passageway disposed in the cover.
2. History of Related Art
As portable radiotelephones, and cellular telephones in particular, become smaller and smaller, it has been increasingly difficult to provide sufficient distance between the speaker, or earpiece, and the microphone providing audio pickup. Typically, small cellular telephones have a cover, commonly referred to as a "flip," which is pivotally mounted to the body of the cellular telephone and covers at least a portion of the telephone such as the keypad. One approach to providing sufficient distance between the speaker and microphone has been to mount the microphone at a distal end of the flip, so that when the flip is in the open position, the microphone is disposed in the approximate area of a user's mouth. However, this approach requires that either an electrical circuit be established through the hinge connection of the flip to the body, or a flexible connector be provided between the flip cover and the body. Both of these arrangements are prone to wear and subsequent degradation of the electrical signal from the microphone to the circuits disposed in the main body of the telephone.
In other cellular telephone arrangements, the microphone has been positioned in the main body of the telephone at a distance as far as possible from the speaker. However, with small instruments, this results in the microphone being positioned at a considerable distance from a typical user's mouth. As a result, audio input quality drops, since the microphone is not near the mouth. The resulting reduction in the voice level of the user also undesirably increases the amount of background noise that is picked up by the microphone.
One attempt to solve the problem of voice pickup in small hand-held radiotelephone instruments is described in European Patent Office Publication No. 0 275 996 B1. The EPO publication provides a sealed acoustical path from a slot in the flip cover to a microphone disposed in the body of the instrument. The acoustical path passes through the hinge connection of the flip cover to the body. The acoustical path is operative when the flip is extended to an open position. However, the arrangement described in the EPO publication has several inherent problems. First, the arrangement does not provide compensation for wear that may occur between the body housing and the flip hinge. As the flip is opened and closed over time, the seal may wear and lose its ability to provide a sealed acoustical path. Secondly, when the flip is closed, the channel through the flip hinge is open, thereby creating an opportunity for material such as lint, food, dirt, and other debris to enter and subsequently block the acoustical path when the flip is open. Thirdly, the fully open position of the flip must be maintained during voice communication so as not to block, or even partially close, the passageway to the microphone. Even small movements of the flip, such as being inadvertently bumped by the user, may cause the flip to become displaced from its fully open position and create misalignment between the acoustical passageway in the flip and the acoustical passageway in the body.
The present invention is directed to overcoming the problems set forth above. It is desirable to have a sealed acoustical path between an aperture provided in the flip cover of a small telecommunication instrument and a microphone disposed in the body of the instrument that has a biased connection between the flip and body to compensate for wear induced by use of the instrument over an extended period of time. It is also desirable to have such an instrument that provides a sealed path through the hinge interconnection of the two components that is closed at all times, eliminating the potential collection of foreign matter and subsequent blockage of the passageway. Furthermore, it is desirable to have such an instrument in which the acoustical path between the flip and body remains open and aligned irrespective of the open, closed, or intermediate position of the flip cover.